Self-crimping fluoropolymer and perfluoropolymer filaments and fibers

ABSTRACT

Disclosed is a method and device for creating three dimensional (3D) self-crimping fluoropolymer(s) and perfluoropolymer(s) filaments via extrusion through a spinneret plate orifice with a hole and elliptical gap and using die swell to close the elliptical gap in the filament forming a seam causing uneven stresses in the longitudinal length of the filament while cooling thereby causing the filament to self-crimp toward the seam.

FIELD OF THE DISCLOSURE

This invention relates to the manufacture and process for the production of self crimping filaments and fibers which are made from extruded thermoplastic materials and relates particularly, but not exclusively to filaments and fibers made from fluoropolymers and perfluoropolymers

BACKGROUND OF THE DISCLOSURE

A number of techniques and processes for producing filaments made from extruded thermoplastic materials are employed well known in the art and are generally extruded through holes in a spinneret plate from a body of the molten plastics material above the spinneret plate. When produced in this manner, the filaments are essentially straight and without crimp. Continuous straight filaments are used for a number of commercial processes, however a crimping of the filament is highly desirable for a number of commercial applications in particular in the clothing or woven material industries.

Crimping provides a filament with high bulk or increased inter filament volume and fiber to fiber cohesion, all are essential characteristics in non-wovens, wovens, fiber filling, carding or yarn spinning of staple fiber yarns.

There are several methods of introducing a crimp to a continuous filament widely in use, virtually all being based on the mechanical deformation of filament by external forces.

One method is by either an inter meshing gear wheel where filaments are forced to take on shape of the gears or by forced compaction causing the filaments to crimp by folding in a confined space (suffer box crimper). The crimp style obtained by these processes has certain limitations in that the crimp lies in only 2 dimensions. The end product is referred to as Zig-Zag or Sawtooth crimp.

Another method is by exerting a very high degree of false twist to heated continuous filament yarn. When the false twist is removed, the yarn retains the curled effect of the false twist.

A further method is that of forced compaction causing the filaments to crimp by folding by using high pressurized hot air within a chamber.

All of the above crimping methods have certain disadvantages, two major issues involving; 1) due to the fact that the crimp is applied by means of external pressure or force, it is not necessarily a permanent crimp, and in some cases the crimp can be easily removed or diminished over time.

2) the fact that these are all secondary processes requiring additional costly equipment and energy consumption and therefore require post processing needs. The use of a stuffer box, in tandem with a separate machine is an example of this need.

Another known method or technique for crimping filaments is to apply cooling or quenching to one side of the extruded thermoplastic forming filaments while the filaments are still in the molten state. As the filaments cool more rapidly on the side facing the direction of the cooling air, thus passing from the molten state to a crystallized state, unequal stresses are created and set across the diameter of the filaments. As orientation and annealing develop, the differential stresses cause a wavy or helical crimp to occur. Generally, the degree of stiffness differential which can be generated using this technique is not sufficient to cause a level of crimping useful in most textile applications.

Another method for creating crimps in a filament is to combine different thermoplastic materials or identical thermoplastic materials with different cooling rates, crystallization rates, and/or glass transition temperatures. The dissimilar materials are maintained within specific configurations with regard to each other within each individual filament either in side-by-side configuration or off-set from the center core. These geometric differences are intentionally created to trap differential stresses such that when phasing through the glass transition temperature range, the different onset of crystallization or glass transition causes stresses on other thermoplastic materials (different or identical), causing the filaments to skew and crimp.

Nonwoven, woven, and knit products may contain any combination of high performance, chemically resistant, temperature resistant fibers which include melt processable perfluoropolymer fibers which act as a binder. The binder fiber either fully or partially melts during the molding or forming process, adhering to the other fibers present. Upon cooling the fully or partially molten binder fiber re-solidifies, locking the other fibers into position thus allowing the nonwoven, woven, or knit product to retain the molded or formed shape.

The perfluoropolymer binder fiber also imparts other benefits, including improved strength, improved dimensional stability, resistance to deformation due to forces such as pressure drop, gravity, and mechanical stress and the potential for a more open and loftier structure leading to lower weight, resistance to compression, and a softer, more cushioned feel.

It is therefore highly desirable to have a method for a self-crimping, flame retardant fluoropolymer or perfluoropolymer as a monofilament, bifilament or multi-component that is economical to produce.

Relevant Art

U.S. Pat. No. 6,811,873, to Nadkarni, Vikas, and assigned to Hills, Inc., describes a method of forming a self-crimping multicomponent fiber comprising passing a plurality of streams of polymer components through a spinneret hole, wherein the plurality of streams includes a first polymer component and a second polymer component. The first and second polymer components are same-polymer components with the first polymer component of a higher viscosity than the second polymer component. The plurality of streams from the spinneret hole are extruded, wherein the streams combine upon emerging from the spinneret hole to form the multicomponent fiber. The multicomponent fiber is quenched and an effective crystallinity differential is established between the first and second polymer components of the multicomponent fiber via at least one parameter selected from the group consisting of; selecting a suitable viscosity differential between the first and second polymer components and selecting a suitable perimeter-to-area ratio of transverse cross-sections of the first and second polymer components.

U.S. Pat. No. 4,418,176, to Streetman, et. al., and assigned to American Cyanamid, Inc., describes a self-crimping, melt-spun acrylonitrile polymer fiber comprising as the continuous fiber matrix a first polymer comprising from about 80 to about 99 weight percent acrylonitrile and from about 1 to about 20 weight percent of one or more monomers. The monomers are copolymerizable with acrylonitrile and heterogeneously dispersed within the fiber matrix with a second polymer selected from the group consisting of polyethylene and polypropylene that are incompatible with the first polymer and also having thermal and/or hydrophilic properties which differ from those of the first polymer by an amount sufficient to provide self-crimping properties to the fiber and constituting the major weight proportion of the fiber.

U.S. Pat. No. 4,301,104, to Streetman, et. al., and assigned to American Cyanamid, Inc., describes a process for producing a self-crimping acrylonitrile polymer fiber which comprises preparing a fusion melt of water and a first polymer comprising from about 80 to about 99 weight percent acrylonitrile and about 1 to about 20 weight percent of one or more monomers copolymerizable with acrylonitrile and a second polymer incompatible with the first polymer and having thermal and/or hydrophilic properties which differ from those of the first polymer by an amount sufficient to provide self-crimping properties in the fiber. The first polymer constitutes the major weight proportion of polymer and the fusion melt, being free of any separate phase of water and/or unmelted polymer, dispersing the second polymer melt heterogeneously within the first polymer melt. Extruding the resultant dispersion through a spinneret directly into a steam-pressurized solidification zone, which is maintained under conditions which control the rate of release of water from the nascent extrudate, enable the extrude to solidify and maintain the solidified extrudate in plastic state. The plastic extrudate is subjected to stretching to provide desirable textile properties therein.

U.S. Pat. No. 7,147,815, to Chang, et. al., and assigned to DuPont, describes a process for preparing a poly(trimethylene terephthalate) bicomponent fiber comprising providing two poly(trimethylene terephthalate) melts, altering the intrinsic viscosity of at least one of the polymers such that after alteration the polymers have intrinsic viscosities that differ by at least about 0.03 dL/g—providing the two poly(trimethylene terephthalate) melts to a spinneret. Spinning the bicomponent fiber from the poly(trimethylene terephthalate) melts the two poly(trimethylene terephthalate) polymer. The melts are prepared by providing two different remelt systems and remelting a poly(trimethylene terephthalate) in each of the remelt systems wherein at least one of the remelt systems is operated so as to provide the poly(trimethylene terephthalate) melts having intrinsic viscosities that differ by at least about 0.03 dL/g.

U.S. Pat. No. 6,054,002, to Griesbach, et. al., and assigned to Kimberly-Clark Worldwide, Inc., describes a method of making a seamless tubular band comprising extruding first molten polymeric components and second molten polymeric components and forming molten multicomponent filaments. The first and second components are substantially consistently positioned in distinct zones across the cross-section of the molten multicomponent filament. The first component comprises a polyolefin and the second polymeric component comprises a non-urethane elastomeric block copolymer. Attenuating the molten multicomponent filaments, by applying an attenuating force to the molten multicomponent filaments as they solidify, wrapping the filaments around a support structure to form a seamless tubular band while maintaining the attenuating force and then removing the tubular band from the support structure, releasing the attenuating force, results in solidified multicomponent filaments contract and self-crimp.

U.S. Pat. No. 5,702,658, to Pellegrin, et. al., and assigned to Owens-Corning Fiberglass Technology, Inc., describes a method for making multicomponent fibers of thermoplastic material comprising supplying at least first and second molten thermoplastic materials to a rotating spinner having an orificed peripheral wall, centrifuging the molten thermoplastic materials through the orifices as molten multicomponent streams of thermoplastic material and cooling the streams to make multicomponent fibers of thermoplastic material.

U.S. Pat. No. 5,701,644, to Kaegi, et. al., and assigned to EMS-Inventa AG, describes a method for producing self-crimped bi-component fibers from a tow of bi-component fibers which have been side-by-side spun from bi-component material. Drawing of the tow to provides a drawn tow, optionally finishing the drawn tow and then relaxing the drawn and optionally finished tow to provide a relaxed tow. The relaxed tow is dried and heat set to provide a heat-set tow. The heat-set tow is optionally cut further improving by post-drawing the drawn tow prior to the optional finishing and relaxing with the post-drawing being carried out in a hot and dry state on a cold drawing unit. After post-drawing, with the tow being in a tensed state and prior to relaxing provides a post-drawn tow with a water coating of between 10 and 30 weight percent, measured prior to relaxation, to provide a water-coated tow. The carrying out the drying of the water-coated tow in a dryer having an inlet and carrying out the relaxing of the water-coated tow at the inlet of the dryer while the water-coated tow is in a compact, closed state to provide bi-component fibers having two-dimensional Ω-crimped bows.

U.S. Pat. No. 4,975,325, to McKinney, et. al., and assigned to Monsanto Corp., describes a self-crimpable nylon 66 yarn wherein the nylon 66 has an RV of at least 50 and contains from 0.02 to 0.5 mole %, based on the theoretical moles of nylon 66 repeat units of chain branching agent. The yarn has an average denier per filament (dpf) of at least 13, a total denier of at least 750, a SAX equatorial/meridional ratio of at least 0.6, an elongation-to-break of less than 120%, a Bulk Test Value of at least 10% and a Luster Test Value of at least 85%.

U.S. Pat. No. 4,720,314, to Black, William B., and assigned to Celanese Corp., describes a process for forming a yarn comprising melt spinning a plurality of polyester filaments having shrinkage peaks and valleys out of phase from filament to filament. One or more of the plurality of filaments is generated by extruding from at least one group of at least two substantially parallel spinneret capillaries at least first and second molten streams of polyester polymer of fiber-forming molecular weight. The first stream is extruded at a greater velocity than the second stream and spaced laterally from the second stream a finite distance selected such that the first and second streams periodically unite below the spinneret to form a combined stream having thick and thin regions; coalescing and attenuating each combined stream and then quenching and solidifying each combined stream into an individual filament having shrinkage peaks and valleys. Each filament from the combined stream is withdrawn at a spinning speed of at least about 1500 meters per minute. The spinning speed, velocities and lateral spacing upon extrusion of the first and second streams is selected such that the shrinkage peaks and valleys along the filament are substantially regular and periodically spaced and the filaments are gathered together into a yarn bundle.

U.S. Pat. No. 4,562,029, to Black, William B., and assigned to Celanese Corp., describes a process for forming a yarn comprising melt spinning a plurality of polyester filaments having shrinkage peaks and valleys out of phase from filament to filament. One or more of the plurality of filaments is generated by the steps comprising extruding from at least one group of at least two substantially parallel spinneret capillaries at least first and second molten streams of polyester polymer of fiber-forming molecular weight. The first stream is extruded at a greater velocity than the second stream and being spaced laterally from the second stream a finite distance selected such that the first and second streams periodically unite below the spinneret to form a combined stream having thick and thin regions. The streams are coalesced and attenuated prior to quenching and solidifying each combined stream into an individual filament. Each filament from the combined stream is withdrawn at a spinning speed of at least about 1500 meters per minute. The spinning speed, velocities and lateral spacing upon extrusion of the first and second streams are selected such that the shrinkage peaks and valleys along the one filament are substantially regular and periodically spaced and gathered together into a yarn bundle.

U.S. Pat. No. 4,661,404, to Black, William B., and assigned to Celanese Corp., describes an as spun latently crimpable yarn which comprises a plurality of polyester filaments. The polyester filaments have a generally oblong, quadrolobal cross section defined by perpendicular major and minor axes with major lobes situated at the ends of the minor axis and minor lobes situated at the end of the major axis. There are substantially regular and periodic variations in thickness along the length of the filaments corresponding to periodic shrinkage peaks and valleys in substantially regular alternating sequence. The shrinkage peaks and valleys are out of phase from filament to filament as spun yarn capable of developing crimp when thermally treated in a relaxed state and having a crimp-to-shrinkage ratio of at least 0.25.

U.S. Pat. No. 4,619,803, to Yu, Jing-peir, and assigned to Monsanto Corp., describes a process for spinning a yarn having latent crimp comprising spinning a plurality of filaments. Each of the filaments are formed by generating first and second sub-streams of a molten polymer with the first sub-stream having a higher temperature than the second sub-stream. The sub-streams are metered at given rates through separate passageways in a spinneret with the passageways being selected and arranged such that the sub-streams unite and merge side-by-side at a point below a plane 0.15 mm above the face of the spinneret to form a combined stream having a relatively cool side comprising a second sub-stream and a relatively hot side comprising the first sub-stream. Quenching air is directed against the combined stream below the spinneret from a given direction to quench the combined stream into a filament. The given direction is selected so that the quench air preferentially impinges on the relatively cool side and withdrawing the filament from the combined stream at a spinning speed above 2500 MPM and converging from filaments at a given distance from the spinneret to form the yarn. The polymer, temperature of the sub-streams, metering rates, given direction, given distance, and spinning speed are selected such that the filament has an elongation below 100% and a bulk of at least 10%.

U.S. Pat. No. 4,489,543, to Bromley, et. al., and assigned to Celanese Corp., describes an as-spun self-crimping yarn comprising a plurality of polyester continuous filaments. The filaments have non-round cross-sectional areas which vary substantially regularly along the lengths of the filaments from regions of large cross-sectional area to regions of small cross-sectional area. The variation in cross-sectional area is more than ±10% about a mean value with the regions of large and small cross-sectional area being out of phase from filament to filament to form a self-crimping yarn.

U.S. Pat. No. 4,419,313, to Bromley, et. al., and assigned to Celanese Corp., describes a process for producing a self-crimping yarn comprising a plurality of variable denier filaments. The filaments are produced by generating two individual streams of molten polyester, of fiber-forming molecular weight with the individual streams traveling at different velocities. The individual streams converge side-by-side to form a combined stream that is quenched. The combined stream is formed into a combined filament and withdrawn at a rate of speed in excess of 3000 meters per minute and selected such that an individual filament quenched from one of the individual streams would have a shrinkage at least ten percentage points higher than that of an individual filament quenched from the other of the individual streams.

U.S. Pat. No. 4,301,102, to Fernstrom, et. al., and assigned to DuPont, describes a process for preparing self-crimpable monocomponent fibers which comprises, in sequence, the steps of melt-spinning a polymer of polyhexamethylene adipamide or polycaproamide into filaments, air-quenching the filaments, contacting the filaments with water and then drawing the filaments. The improvement comprises quenching the filaments to an average surface temperature in the range of about 40° to 130° C. by a cross-flow of air having an average velocity of less than 3 meters per second and applying to the filaments, while at the surface temperature, an effective amount of an aqueous liquid. The filaments are drawn without any external heating at a draw ratio of at least 1.3:1 to provide the filaments with a tenacity of at least 1.3 grams per denier, a break elongation of no greater than 120% and an ability, when subjected to a heat relaxation treatment, to develop a substantially helical, frequently reversing crimp of at least 6 filament crimp index.

U.S. Pat. No. 4,343,860, to Fernstrom, et. al., and assigned to DuPont, describes a self-crimpable, monocomponent, nonbulbous, drawn fiber of polyhexamethylene adipamide or of polycaproamide, having a crystal perfection index of no greater than 70, a tenacity of at least 1.3 grams per denier and a break elongation of no greater than 120%, which upon being subjected to a relaxed heat treatment develops a substantially helical, frequently reversing crimp with at least 6 filament crimp index.

U.S. Pat. No. 4,246,747, to Plunkett, et. al., and assigned to Fiber Industries, Inc., describes a process for producing a latent heat bulkable polyethylene terephthalate yarn comprising melt spinning a polyethylene terephthalate fiber-forming polymer into a plurality of filaments, cooling the melt-spun filaments below the second order transition temperature, dividing the filaments into at least two groups, subjecting at least one group of filaments to a heat treatment at a temperature above the second order transition temperature, recombining the filaments into a yarn and taking up the yarn at a speed in excess of 8000 feet per minute and subsequently subjecting the yarn to a heat treatment at a temperature of 100 to 225 degrees centigrade in a relaxed state to differentially shrink said yarn and develop bulk.

U.S. Pat. No. 4,238,439, to Hyun, Jae C., and assigned to Monsanto Corp., describes a melt spinning process for producing a multifilament polyamide yarn having at latent bulk of at least 18% comprising extruding at a given extrusion rate through spinneret orifices of trilobal or triskellion cross-section a fiber-forming polyamide consisting essentially of randomly recurring units of a formula wherein the mole ratio of (i) units to (ii) units is in the range of from about 90:10 to about 99:1, to form a molten stream, differentially quenching the molten streams by exposing one side thereof to transversely flowing air in a cooling zone to provide filaments, withdrawing the filaments from the cooling zone by passing the filaments around at least one rotatable roll with a least a partial wrap and collecting the filaments under tension on a take-up bobbin. The peripheral speed of the rotatable roll(s) is at least 2000 yards (1828.8 meters) per minute and is correlated with the extrusion rate to provide a drawn yarn having a denier per filament of at least 18 and wherein the filaments have a modification ratio greater than 1.2 and less than 4.0.

U.S. Pat. No. 4,332,758, to Blackmon, et. al., and assigned to Monsanto Corp., describes a process for producing a self-crimping yarn comprising first and second types of filaments. The process comprises spinning the first filament type by forming a first plurality of melt spun filaments by merging molten polyester streams traveling at different extrusion speeds to form thick and thin regions in the merged streams out of phase from other merged streams. The first plurality of merged streams is quenched into the first type of filaments along their lengths and out of phase from filament to filament; spinning the second of filament type by extruding other streams of molten polymer of fiber forming molecular weight from helical orifices selected to give filaments with helical cross-sections and lower shrinkages than the combined filaments at a given common spinning speed and quenching the other streams into filaments; withdrawing the first and said second types of filaments from the streams at the common spinning speed and combining the first and second types of filaments into a yarn. The thick and thin regions in the first plurality of molten streams and the common spinning speed is selected such that the yarn has a crimp of at least 2%.

U.S. Pat. No. 4,330,591, to Blackmon, et. al., and assigned to Monsanto Corp., describes a multifilament yarn comprising first and second classes of filaments with each of the first class of filaments being polyester and having shrinkage profiles in the form of shrinkage peaks and valleys along their lengths. The shrinkage peaks and valleys are out of phase from filament to filament and have amplitudes and spacings along each of the filaments of the first class selected such that the yarn has a crimp above 2%. Also, each of the second class of filaments has a spiral cross-section and a lower shrinkage than the shrinkage of the filaments of the first class.

U.S. Pat. No. 4,522,773, to Menezes, et. al., and assigned to Celanese Corp., describes a process for expeditiously forming and structurally modifying a latently self-crimping polyester yarn comprising a plurality of polyester filaments having thick and thin regions along their lengths which are out of phase from filament to filament. The filaments are generated by the steps comprising forming a plurality of combined streams of melt spun polyester by combining at least first and second extruded molten streams of fiber forming polyester traveling at different extrusion speeds to form thick and thin regions in the combined streams out of phase from other combined streams. The combined streams are quenched to transform into solid filaments having thick and thin regions along their lengths that are out of phase from filament to filament in a solidification zone provided with a gaseous atmosphere at a temperature below the glass transition temperature of the polyester. The resulting filaments in the direction of their lengths are passed through a conditioning zone providing a gaseous atmosphere at a temperature sufficient to decrease the percentage yarn shrinkage of the resulting filaments and to produce polyester filaments which exhibit a percentage yarn shrinkage in the range of from about 10 to about 45 percent and withdrawing the resulting filaments from the conditioning zone at a substantially constant wind-up speed in the range of from about 2200 to about 4400 yards per minute.

U.S. Pat. No. 3,996,327, to Ohtomo, et. al., and assigned to Nipon Kynol, Inc., describes a method of producing a self-crimping phenolic composite fiber having heat-resistant and flameproof properties. The method comprises melt-spinning a modified phenolic resin obtained by melt blending a heat-meltable uncured novolak resin with 0.5-30% by weight, based on the total weight of the mixture, of a heat-meltable fiber-forming resin selected from polyamide resin, polyester resin, polyurethane resin or polyolefin resin and a heat-meltable uncured novolak resin, with the melt-spinning being carried out such that the components are united in an eccentric or side-by-side relationship and curing the phenolic resin component contained in the resulting heat-meltable composite fiber.

U.S. Pat. No. 4,424,258, to Bach, Hartwig C., and assigned to Monsanto Corp., describes a process for producing a self-crimping, multi-component filament, comprising co-extruding at a given speed (extrusion speed) at least two molten fiber-forming components in a side-by-side or asymmetric sheathcore configuration to form a molten multicomponent filament. One of the components comprises a polyester containing a minor amount of polyolefin dispersed therein and the other component(s) comprises a polyester of the same chemical structure containing a lesser amount of polyolefin. The molten filament is cooled in a quenching zone to form a solid filament. Attenuating and accelerating the filament from its point of formation, by withdrawing the solidified filament from the quenching zone at a speed (spinning speed) which is greater than the extrusion speed, the extrusion speed, amount of polyolefin in the components, spinning speed and denier of the filament are correlated to provide an as-spun filament having a total bulk of at least 10% and the polyolefin consists essentially of recurring units of the formula —CH2 CRR′— where R and R′ are atoms or radicals which do not render the polyester incapable of forming fibers.

U.S. Pat. No. 5,972,502, to Jesse, et. al., and assigned to Optimer, Inc., describes a fiber which comprises a non-elastomeric polyamide and a thermoplastic elastomer selected from the group consisting of a polyether block polyamide copolymer and a polycaprolactone polyester, wherein the fiber is self-crimping.

U.S. Pat. No. 6,123,886, to Slack, Phillip Trevor, and assigned to SDS Consultancy Svcs., describes a method for producing a continuous filament by extrusion of molten thermoplastic material through a spinneret plate having holes of a cross-sectional configuration that is determinative of the cross-section of the formed filament. The method comprises the steps of generating a turbulence in the molten thermoplastic material intended to form the filament, immediately prior to, or at the point of, formation of the filament, whilst the thermoplastics material is in its glass transition phase and maintaining stresses induced in the formed filament by the turbulence whilst the filament material passes into its crystallised phase, and forming filaments having a substantial helical crimp by extruding the molten thermoplastic material through holes in the spinneret plate.

PCT Publication No. WO04094706A1, to Kim, et. al., and assigned to Huvis Corp., describes a method of manufacturing a polyester conjugated yarn comprising subjecting two types of polymers having a large intrinsic viscosity difference to component spinning in a spindraw process by use of an inclined circular spinneret so as to cause the polymers to have a side-by-side sectional structure. The two types of polymers are polyethyleneterephthalate with intrinsic viscosity of 0.45-0.65 as a first polymer and polytrimethyleneterephthalate with intrinsic viscosity of 0.90-1.10 as a second polymer. The polyester conjugated yarn has a cross section satisfying Equations I and 2, below: Equation I O &lt; (interface ratio=length of Idle CD. length of line AB) 0.6 Equation 2 1 &lt; (shape ratio=length of line EF. length of line GH) &lt; 1.4 1 5 wherein, line AB is a length of a long axis of an interface between a high viscosity polymer and a low viscosity polymer; line CD is a length of a short axis of an interface between a high viscosity polymer and a low viscosity polymer, line EF is a maximum length of a long axis of a cross section of a yarn and line Gl 1 is a maximum length of a short axis of a cross section of a yarn.

PCT Publication No. WO04061169A1, to Chang, et. al., and assigned to DuPont, describes a process for preparing a poly(trimethylene terephthalate) bicomponent fiber comprising providing two poly(trimethylene terephthalate) melts, altering the intrinsic viscosity of at least one of the polymers such that after alteration the polymers have intrinsic viscosities that differ by at least about 0.03 dL/g, providing the two poly(trimethylene terephthalate) melts to a spinneret and spinning bicomponent fiber from the poly(trimethylene terephthalate) melts.

PCT Publication No. WO03029541A1, to Stantis, et. al., and assigned to Extreme Fibers Inc., describes a web or fabric made with high performance fibers or filaments. The fibers and filaments have properties such as high melting, chemical resistance, non-burning, strong, non-wetting, high purity. The web also containing fibers or filaments with individual deniers between 0.5 and 300 made from melt processable perfluoropolymers where the fabric is thermally treated so as to allow the melt processable perfluoropolymer fibers and yarns to partially, or fully, melt and adhere to the other fibers in the web or fabric matrix. The fabric or web is capable of being molded, drawn, or formed using pressure or vacuum prior to the thermal treatment process, then fixed into place during the thermal treatment process, making a high performance fabric or web article.

PCT Publication No. WO0118289A1, to Cistone, et. al., and assigned to Extreme Fibers Inc., describes textured yarns having 2 to 100 crimps/inch derived from melt processable perfluoropolymers and having individual filament deniers from about 0.5 to about 300 and total yam deniers of about 10 to 100,000. The perfluoropolymer is selected from the group consisting of copolymers of tetrafluoroethylene with 1 to 5 mole % of at least one perfluoroalkoxylvinylether where the alkyl group has from 1 to 4 carbon atoms and copolymers of tetrafluoroethylene with 2 to 20 mole % of at least one perfluoroolefm having from 3 to 8 carbon atoms.

PCT Publication No. WO0104395A1, to Haigh, Joshua and unassigned, describes a method of making fibers with a curl comprises causing continuous filaments to pass a heated member whereby a temperature differential across the filaments is induced and subsequently taking lengths of fiber from the filaments whereby the fibers have a curl as a result of the temperature differential having been induced.

SUMMARY OF THE DISCLOSURE

Disclosed is a device and method for producing self-crimping fluoropolymer(s) and perfluoropolymer(s) fillers and filaments.

By definition: A die swell—(Burrus Effect, Melt Bulge)—occurs when a polymer attempts to recover the form it had prior to being squeezed through the spinneret orifice. When the polymer leaves the orifice, the stresses are relieved in the form of elastic recovery. Die swell results in strands of polymer material that are initially larger in cross sectional area than the orifice from which they exuded and attempt to mimic and essentially maintain the shape of the orifice, even after the subsequent attenuation and cooling. The polymer shape is generally controlled by final diameter depending on the die orifice size, shape, and process conditions. In the disclosure summary, the die orifice shape, with an included cove portion, causes a higher degree of die swell in the cove portion relative to the die swell from the periphery of the circular portion of the hole. The increased die swell to the cove portion fills in the gap left by the hole shape, resulting in sufficient stress differences to crimp, twist, and bend the extruded filaments in a controlled manner.

Disclosed is a device and method for self-crimping fluoropolymer(s) and perfluoropolymer(s) wherein fluoropolymer(s) and/or perfluoropolymer(s) are heated to a molten state and extruded under pressure through a spinneret plate orifice as a filament that exhibits included die swell to a particular cross sectional area of a filament wherein the filament in a glass transition temperature range providing conditions for expansion sectionally along a longitudinal length of the filament and wherein opposing sides of a gap created in one section of the filament by the spinneret orifice fill creating a seam between the opposing sides thereby providing uneven stresses to one portion of the filament as the filament cools. This uneven stress development causes the filaments to crimp, bend, deform and/or twist toward the seam in a preferred manner.

Another embodiment of the present disclosure includes a spinneret orifice which is not circular but causes an excessive die swell in the area of the elliptical cove, thus producing a filament which is circular in cross-section.

Another embodiment of the present disclosure includes a spinneret orifice that is essentially a hole with an elliptical cove portion for creating an elliptical gap along a longitudinal length of filament.

Another embodiment of the present disclosure is fluoropolymer(s) and perfluoropolymer(s) when extruded through the spinneret orifice with an elliptical cove portion and the effect of included die swell occurs, the fluoropolymer(s) and perfluoropolymer(s) filament will crimp, bend, deform and/or twist toward the seam as a 3-dimensional (3D) self-crimping filament.

Another embodiment of the present disclosure is that the fluoropolymer(s) and perfluoropolymer(s) may be extruded in a horizontal plane or vertical plane.

Another embodiment of the present disclosure is that the fluoropolymer(s) and perfluoropolymer(s) may be extruded in a horizontal plane with the spinneret orifice cove in an upward position.

Another embodiment of the present disclosure is that the fluoropolymer(s) and perfluoropolymer(s) filament may be extruded as staple fiber “short spin” or as “long spin” continuous filament.

Another embodiment of the present disclosure is that the fluoropolymer(s) and perfluoropolymer(s) filament may be pulled in a straight line or at an angle from the spinneret orifice.

Another embodiment of the present disclosure is to improve the appearance, properties and performance characteristics of self-crimping fluoropolymer(s) and perfluoropolymer(s) filament and associated products.

Another embodiment of the present disclosure is a device and method that will create self-crimping filaments of any blend of polyamide, polyester, polypropylene, polyetheretherketone (PEEK), polyvinylacetate (PVA), polyphenylenesulfide (PPS), polylactide (PLA), polybutylene terephthalate (PBT), perfluoropolymers and/or other polymeric compositions.

Another embodiment of the present disclosure is to provide fluoropolymer and/or perfluoropolymer filaments to make a variety of self-crimped fluoropolymer(s) and/or perfluoropolymer(s) woven, non-woven and knitted forms.

Another embodiment of the present disclosure to provide 3D self-crimped fluoropolymer(s) and/or perfluoropolymer(s) filaments that may be used via conventional techniques to make filtration support media.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 describes extrusion process with die swell.

FIG. 2A describes the disclosed spinneret orifice with elliptical cove.

FIG. 2B is a top view of the spinneret and elliptical cove orifice and a description of how the self-crimping seamed filament is formed, but is not a similar cross sectional shape to the spinneret hole which initially created the filament.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a molten polymer [110] being injected through an injector tube [115] under pressure [120] into and through a spinneret orifice [125] in a spinneret plate(s) [127] that may be of various shapes and sizes depending on the filament [130] desired. As the molten polymer [110] passes through the spinneret orifice [125] at a temperature higher than the glass transition temperature of the polymer, the molten polymer [110] expands, in a condition known as die swell [135], and tries to return the molten polymer [110] to its original shape by expanding after passing through the spinneret orifice [125]. The desired shape of the filament [130] is dependent on controlling the process parameters, such as temperature, injection pressure, spinneret orifice [125] size and shape. Most of the spinneret orifice [125] shapes are symmetrical, which allow for creation of a straight or slightly curvy filament [130]. This slightly curved shape is enhanced by a post drawing process. It is, however, desirable to create a filament [130] that is crimped, tightly twisted, spiraled, bent or zig zagged. Presently previous post operations physically subject the filament [130] to deformation due to crimping gears to obtain a crimped filament (not shown) & this technique eliminates the need for post operations.

FIG. 2A discloses a molten polymer [110] being injected through an injector tube [115] under pressure [120] into and through a spinneret plate orifice [240] in a spinneret plate [127] to form a self-crimping filament [245].

FIG. 2B is a top view of the spinneret orifice [240] which is shaped as a round hole with an ellipsoid cove peninsula [220] at the top. The molten polymer [110] passes through the spinneret plate orifice [240] in the manner described in FIGS. 1A and 1B, with the exception being that the ellipsoid cove [220] causes shape revision exhibited by die swell [135] of the molten polymer [110] to fill the ellipsoid cove gap [225] in the self-crimping filament [245]. The ellipsoid cove gap [225] closes and hardens causing a lower stress on the molten polymer [110] in that, when closed, creates a molecular/crystalline seam [250] (shown by a dotted line) structure with a consistent differential stress that causes the self-crimping filament [245] to crimp, bend, deform and/or twist in a preferred manner.

The advantage of the spinneret plate orifice [240] disclosed in the present application is the ellipsoid cove [220], in that the cross section of the resulting self-crimping filament [245], does not nearly resemble the symmetry or shape of the spinneret plate orifice [240]. Complete closure resulting in a seam [250] of the ellipsoid cove gap [225] may be controlled partially by process and/or controls, but is mostly controlled by the spinneret plate orifice [240] controlling the amount of crimping, bending, deformation and/or twisting. 

1. A method for self-crimping fluoropolymer(s) and perfluoropolymer(s) comprising; heating said fluoropolymer(s) and/or said perfluoropolymer(s) to a molten state, extruding said fluoropolymer(s) and/or said perfluoropolymer(s) under pressure through spinneret plate(s) orifice(s) creating a filament or filaments that exhibit die swell, wherein said filament(s) in a glass transition temperature range expand sectionally along a longitudinal length of said filament, and wherein said spinneret plate orifice(s) comprise a round hole shape with an ellipsoid peninsula creating an ellipsoid cove gap in one section of said filament and opposing sides of said ellipsoid cove gap close creating a seam between said opposing sides such that differential die swell around said ellipsoid cove gap creates uneven stresses along one portion of said filament thereby causing said filament to crimp, bend, deform and/or twist toward said seam in a preferred manner.
 2. The method of claim 1, wherein differential cooling is provided in that said seam between opposing sides of said filament allows for slower cooling within said filament than cooling of the external surfaces of said filament, providing uneven stresses to one portion of said filament as said filament cools, thereby causing said filament to crimp, bend, deform and/or twist toward said seam in a preferred manner.
 3. The method for self-crimping fluoropolymer(s) and perfluoropolymer(s) as in claim 1, wherein said spinneret plate orifice is a hole with an ellipsoid cove peninsula for creating said ellipsoid cove gap along said longitudinal length of said filament and wherein the rate of cooling of said filament allows for control of said stresses within said filament.
 4. The method for self-crimping fluoropolymer(s) and perfluoropolymer(s) as in claim 1, wherein said fluoropolymer(s) and/or said perfluoropolymer(s) extruded through said holes with said ellipsoid cove gap incurring said die swell, said filament will crimp, bend, deform and/or twist toward said seam to provide a 3-dimensional helical crimped filament that may or may not be spiraled.
 5. The method for self-crimping fluoropolymer(s) and perfluoropolymer(s) as in claim 1, wherein said fluoropolymer(s) and perfluoropolymer(s) may be extruded in a horizontal plane, a vertical plane or any angle in between said horizontal or said vertical plane.
 6. The method for self-crimping fluoropolymer(s) and perfluoropolymer(s) as in claim 1, wherein extruding said filament may be either a staple fiber produced during short and optionally discontinuous drawing and/or chopping time periods or as long continuous filaments produced during long and optionally discontinuous drawing and/or chopping periods time periods.
 7. The method for self-crimping fluoropolymer(s) and perfluoropolymer(s) as in claim 1, wherein pulling said filament may be in a straight line or at an angle from said spinneret plate orifice.
 8. The method for self-crimping fluoropolymer(s) and perfluoropolymer(s) as in claim 1, wherein improving concentricity of said filament results in improved appearance, properties and performance characteristics as well as strengthening said filament and products comprised of said filament.
 9. The method for self-crimping fluoropolymer(s) and perfluoropolymer(s) as in claim 1, wherein said filaments are self-crimping filaments comprising a combination of any blend of polyamide, polyester, polypropylene, PEEK, PES, PVA, PPS, PLA, PBT, perfluoropolymers, and/or liquid crystal polymers.
 10. The method for self-crimping fluoropolymer(s) and perfluoropolymer(s) as in claim 1, wherein said filaments are provided to produce a variety of woven, non-woven and knitted forms.
 11. The method for self-crimping fluoropolymer(s) and perfluoropolymer(s) as in claim 1, wherein self-crimping techniques provide filaments that are individually or collectively useful as filtration support media.
 12. A device for self-crimping fluoropolymer(s) and perfluoropolymer(s) comprising; heating said fluoropolymer(s) and/or said perfluoropolymer(s) to a molten state, extruding said fluoropolymer(s) and/or said perfluoropolymer(s) under pressure through spinneret plate(s) orifice(s) creating a filament or filaments that exhibit die swell, wherein said filament(s) in a glass transition temperature range expand sectionally along a longitudinal length of said filament, and wherein said spinneret plate orifice(s) comprise a round hole shape with an ellipsoid peninsula creating an ellipsoid cove gap in one section of said filament and opposing sides of said ellipsoid cove gap close creating a seam between said opposing sides such that differential die swell around said ellipsoid cove gap creates uneven stresses along one portion of said filament thereby causing said filament to crimp, bend, deform and/or twist toward said seam in a preferred manner.
 13. The device for self-crimping fluoropolymer(s) and perfluoropolymer(s) as in claim 1, wherein said spinneret plate orifice is a hole with an ellipsoid cove peninsula for creating said ellipsoid cove gap along said longitudinal length of said filament and wherein the rate of cooling of said filament allows for control of said stresses within said filament.
 14. A self-crimping fluoropolymer(s) or perfluoropolymer(s) filament wherein said filament comprises; heating said fluoropolymer(s) and/or said perfluoropolymer(s) to a molten state, extruding said fluoropolymer(s) and/or said perfluoropolymer(s) under pressure through a spinneret plate orifice with one or more holes, creating said filament that exhibits die swell, wherein said filament, as a molten polymer, expands to fill a plowed furrow in a specific section of said filament, and wherein said spinneret plate of one or more orifices creates a single or multiple ellipsoid cove gap in one section of said filament and a corresponding fill, creating a seam between said opposing sides.
 15. The filament of claim 14, wherein differential cooling is provided in that said seam between opposing sides of said filament allows for slower cooling within said filament than cooling the external surfaces of said filament, providing uneven stresses to one portion of said filament as said filament cools, thereby causing said filament to crimp, bend, deform and/or twist toward said seam in a preferred manner.
 16. The filament of claim 14, wherein said spinneret plate orifice includes one or more holes with an ellipsoid cove peninsula for creating said ellipsoid cove gap along said longitudinal length of said filament.
 17. The filament of claim 14, wherein as said filament is extruded through said holes with said ellipsoid cove gap incurring said die swell, said filament will crimp, bend, deform and/or twist toward said seam to provide a 3-dimensional helical crimped filament that may or may not be spiraled.
 18. The filament of claim 14, wherein said filament may be extruded in either a horizontal plane or a vertical plane.
 19. The filament of claim 14, wherein producing said filament extrusion is the result of either a chopped staple fiber produced during short and optionally discontinuous spinning time periods or as a long continuous filaments produced during long spinning time periods.
 20. The filament of claim 14, wherein pulling said filament may be in a straight line or at an angle from said spinneret plate orifice.
 21. The filament of claim 14, wherein concentricity results in improved appearance, properties and performance characteristics as well as strengthening said filament and products comprised of said filament.
 22. The filament of claim 14, wherein said filaments are self-crimping filaments of polyamide, polyester, polypropylene, PEEK, PES, PVA, PPS, PLA, PBT, perfluoropolymers, and liquid crystal polymers or polymeric compositions comprising blends of any of polyamide, polyester, polypropylene, PEEK, PES, PVA, PPS, PLA, PBT, perfluoropolymers, and liquid crystal polymers.
 23. The filament of claim 14, wherein said filaments are provided to produce a variety of woven, non-woven and knitted forms.
 24. The filament of claim 14, wherein self-crimping techniques provide filaments that are individually or collectively useful as filtration support media. 